The invention relates to a radio relay arrangement for extending the range on the radio link, connecting radio communication subscriber stations with a radio base station, of a telecommunication system.
The operation of such a radio relay arrangement requires that the totality of available radio channels is utilized as well as possible. It is a further requirement that the signal delays are not excessive even when a plurality of such radio relay arrangements are connected in cascade.
Finally, the objective must be that the use of such radio relay arrangements is possible while largely retaining the standards applicable to the radio link of the telecommunication system. Such standardization can be, for example, the DECT (Digital European Cordless Telecommunications) standard which has been defined by the European Telecommunication Standards Institute (ETSI).
ETSI also has already described two proposals for such radio relay arrangements, one of which, however, only represents a satisfactory solution with respect to the abovementioned requirements of good utilization of the radio channels and major retention of the existing standard, and the other one of which only represents a satisfactory solution with respect to the maintenance of small signal delays, which will be discussed in still more detail in the text which follows.
It is an object of the present invention to provide an improved radio relay arrangement.
In general terms the present invention is a radio relay arrangement for extending the range on the radio link, connecting radio communication subscriber stations with a radio base station, of a telecommunication system. It provides the same interface relationships toward the radio communication subscriber stations and toward the radio base station as they are preferably given according to standard in a radio link without relays. Accordingly, in each case a pair of time slots, spaced apart from one another by half the time-frame length and having the same position in periodically repetitive time frames, is used for the radio transmissions of the up direction and down direction, belonging to the same call. In this arrangement in each case radio transmissions of the same one or other direction of transmission take place in the two halves of the time frames. If it consists of a plurality of cascaded parts, it provides between these parts interface relationships according to which a pair of time slots which are not tied to the spacing by half the time-frame length, are arranged advantageously with respect to the minimization of the total transmission time but in any case belong to the time-frame half allocated to the relevant direction of transmissions.
Advantageous developments of the present invention are as follows.
For a subdivision into a number of cascaded parts, in each case at least two pairs of time slots, spaced apart by half the time-frame length according to standard, of the up direction of transmission and of the down direction of transmission is used, between in each case two cascaded parts, for forming the pairs not tied to the spacing by half the time-frame length, that he set of time slots of the pairs not tied to the spacing by half the time-frame length is completely contained in the set of the pairs tied to the spacing by half the time-frame length.
For a number of simultaneous calls at the interfaces between the cascaded parts, in each case no more than N pairs of time slots, which are spaced apart by half the time-frame length according to standard, are used for forming the desired time-slot pairs not tied to the spacing by half the time-frame length so that all time slots occupied in the sense of the standard are actually used for transmitting information.
The standard interface conditions correspond to the DECT standard.
Accordingly, the radio relay arrangement according to the invention provides, on the other hand, externally, that is to say toward the radio communication subscriber stations and toward the radio base station, interface relationships which correspond to the standardized interface relationships on a radio link without radio relay arrangement, and, on the other hand, when the radio relay arrangement consists of a number of cascaded parts, interface relationships which keep the signal delays, which are critical in such cascading arrangements, to a sensibly small size and, nevertheless, largely prevent the risk of blocking due to a lack of suitable time slots, are provided for the interfaces between these parts, that is to say internally.